Air Pump noise caused by the Compressor ???
06-16-2008, 11:14 PM
#1
Instructor
Thread Starter
Air Pump noise caused by the Compressor ???
Here's a strange one.
After recharging my A/C with R12, it was working great (43.5 degrees at the vent), but seemed to be causing a cackling noise and low resonance vibration just off idle -- right around 900-1100 RPM. I'd heard compressors on their way out on a couple of different cars, but had never heard that kind of sound only at a specific RPM. With the A/C off, the sound disappeared, so I was sure it was related to the compressor.
I put an oil and conditioner charge in the compressor but no change. Then I noticed that the sound didn't seem to be coming exactly from the compressor. I got a gift wrap paper roll and started listening to the compressor and things around it. Sure enough, the sound was coming from the AIR PUMP.
So...... when I have the A/C on, and rev the engine to 900-1100 RPM, the air pump emits a cackling sound, with a strong enough low resonance that from inside the car, it sounds like moaning from the engine back thru the exhaust. All I can figure is that the compressor emits a vibration at 900-1100 RPM that causes something in the air pump to resonate loudly. Very weird.
Anyone ever heard of something like this? Suggestions?
Thanks in advance -- Dave
After recharging my A/C with R12, it was working great (43.5 degrees at the vent), but seemed to be causing a cackling noise and low resonance vibration just off idle -- right around 900-1100 RPM. I'd heard compressors on their way out on a couple of different cars, but had never heard that kind of sound only at a specific RPM. With the A/C off, the sound disappeared, so I was sure it was related to the compressor.
I put an oil and conditioner charge in the compressor but no change. Then I noticed that the sound didn't seem to be coming exactly from the compressor. I got a gift wrap paper roll and started listening to the compressor and things around it. Sure enough, the sound was coming from the AIR PUMP.
So...... when I have the A/C on, and rev the engine to 900-1100 RPM, the air pump emits a cackling sound, with a strong enough low resonance that from inside the car, it sounds like moaning from the engine back thru the exhaust. All I can figure is that the compressor emits a vibration at 900-1100 RPM that causes something in the air pump to resonate loudly. Very weird.
Anyone ever heard of something like this? Suggestions?
Thanks in advance -- Dave
06-17-2008, 12:04 AM
#2
Le Mans Master
Here's a strange one.
After recharging my A/C with R12, it was working great (43.5 degrees at the vent), but seemed to be causing a cackling noise and low resonance vibration just off idle -- right around 900-1100 RPM. I'd heard compressors on their way out on a couple of different cars, but had never heard that kind of sound only at a specific RPM. With the A/C off, the sound disappeared, so I was sure it was related to the compressor.
I put an oil and conditioner charge in the compressor but no change. Then I noticed that the sound didn't seem to be coming exactly from the compressor. I got a gift wrap paper roll and started listening to the compressor and things around it. Sure enough, the sound was coming from the AIR PUMP.
So...... when I have the A/C on, and rev the engine to 900-1100 RPM, the air pump emits a cackling sound, with a strong enough low resonance that from inside the car, it sounds like moaning from the engine back thru the exhaust. All I can figure is that the compressor emits a vibration at 900-1100 RPM that causes something in the air pump to resonate loudly. Very weird.
Anyone ever heard of something like this? Suggestions?
Thanks in advance -- Dave
After recharging my A/C with R12, it was working great (43.5 degrees at the vent), but seemed to be causing a cackling noise and low resonance vibration just off idle -- right around 900-1100 RPM. I'd heard compressors on their way out on a couple of different cars, but had never heard that kind of sound only at a specific RPM. With the A/C off, the sound disappeared, so I was sure it was related to the compressor.
I put an oil and conditioner charge in the compressor but no change. Then I noticed that the sound didn't seem to be coming exactly from the compressor. I got a gift wrap paper roll and started listening to the compressor and things around it. Sure enough, the sound was coming from the AIR PUMP.
So...... when I have the A/C on, and rev the engine to 900-1100 RPM, the air pump emits a cackling sound, with a strong enough low resonance that from inside the car, it sounds like moaning from the engine back thru the exhaust. All I can figure is that the compressor emits a vibration at 900-1100 RPM that causes something in the air pump to resonate loudly. Very weird.
Anyone ever heard of something like this? Suggestions?
Thanks in advance -- Dave
06-17-2008, 12:17 AM
#3
Instructor
Thread Starter
Thx - Dave
06-17-2008, 09:42 PM
#5
Instructor
Thread Starter
Does tightening help? Anything else?
